Subject: Re: RFC 1323 and www.netbsd.org
To: Jan Schaumann <firstname.lastname@example.org>
From: Steven M. Bellovin <email@example.com>
Date: 09/10/2004 10:39:18
In message <20040910142538.GD11936@netmeister.org>, Jan Schaumann writes:
>Content-Type: text/plain; charset=us-ascii
>I just saw this message on German Usenet that, summarized says:
>,----[ from usenet article ]
>| www.netbsd.org can't be reached without ever timing out. The reason for
>| this is that a gateway throws away non-standard packets received from
>| www.netbsd.org. Reference:
>| "When the TCP timestamp option (RFC 1323) is used
>| the extra 12 bytes aren't taken into account when creating a packet so
>| the packet ends up being 12 bytes larger than the maximum segment size
>| announced by the correspondent host + 40 bytes for IP+TCP headers"
>| If the user uses
>| sysctl net.inet.tcp.rfc1323=3D0
>| under OpenBSD or FreeBSD, the page is loaded normally.
>Without having investigated this at all, does anybody here know if that
>is actually the case and what, if anything, we can do about this?
I haven't verified the code; however, according to Section 18.104.22.168 of
RFC 1122, the complainant's interpretation of the spec is correct. The
actual segment size used must take into account the TCP option size.
--Steve Bellovin, http://www.research.att.com/~smb